Objectives: 1- To compare sleep characteristics of children with autism, as measured with questionnaires filled by parents and laboratory polysomnography; 2- To evaluate the relationship between sleep characteristics in children with autism and core symptoms of autism.
Methods: Thirteen boys diagnosed with autism according to DSM-IV criteria (ASD: 10.7 ± 1.9 years) and 21 typically-developing boys (10.7 ±1.7) spent 2 consecutive nights in a sleep laboratory. All had a normal IQ and were free of psychiatric or neurologic conditions. None reported difficulties with sleep. Sleep was evaluated in two ways: 1) The Children’s Sleep Habits Questionnaire (CSHQ), filled by parents; 2) Polysomnographic recordings. The ADI-R (current scores) measured daytime functioning. Groups were compared using t-tests for independent samples. Pearson’s correlation coefficients evaluated the association between sleep and daytime functioning.
Results: The CSHQ showed that ASD children have more problems than TD children with sleep onset delay and sleep duration. Compared to the TD group, polysomnographic recordings of ASD children showed a longer sleep latency (30.4 ± 7.2 min, vs. 13.5 ± 4.6; p=0,006), more awakenings (15.54 ± 2.47 min, vs. 13.97 ± 2.31; p=0.055 ), less slow-wave sleep (18.4 ± 0.8 %, vs. 24.0 ± 1.3 %; p=0.002), but the same amount of REM sleep (18,9 ± 0,9 %, vs. 17,0 ± 1,0; p=0,186). The density of EEG sleep spindles per hour of stage 2 was the same over the central electrodes (294.4 ± 32.0, vs. 288.4 ± 26.7; p= p=0.70) but inferior over the frontal electrodes (147.1 ± 19.6 vs. 213.0 ± 26.9; p= p=0.08). In the ASD group, CSHQ sleep latency showed a positive correlation with ADI-R on the communication (r=0.72; p=0.008) and the repetitive behavior scale (r=0.665; p= 0.018) sum scores; CSHQ daytime sleepiness showed a positive correlation with the ADI-R socialization sum score (r= 0.590; p=0.043); PSG sleep efficiency showed a negative correlation with the ADI-R on the communication sum score (r= -0.742, p=0.006).
Conclusions: Objective and subjective measures show signs and symptoms of alterated sleep in children with autism. Sleep atypicalities in children with autism is associated with prototypicality of the autism phenotype: the more the sleep is modified in comparison to typical individuals, the higher are the scores indexing the atypicality of the autism phenotype.
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